Lawrence M. Weiss, MD

Carcinoma of an unknown primary site is a common clinical syndrome, accounting for approximately 3% of all oncologic diagnoses. Patients in this group are heterogeneous, having a wide variety of clinical presentations and pathologic findings.

Carcinoma of an unknown primary site is a common clinical syndrome, accounting for approximately 3% of all oncologic diagnoses. Patients in this group are heterogeneous, having a wide variety of clinical presentations and pathologic findings. A patient should be considered to have carcinoma of an unknown primary site when a tumor is detected at one or more metastatic sites, and routine evaluation (see below) fails to define a primary tumor site.